PLATE 18 
Corn plants showing effect of various chemical compounds on nodal tissues. 
A. —Effect of 30 cc. of iron citrate in 1 per cent solution upon the nodal tissues. 
The vascular plate tissues are darkened, and the leaves are wilted and killed. The 
plant responded in this manner in three days. 
B. —Ferrous sulphate in % per cent solution is very toxic. The vascular plate tissues 
are disintegrated very rapidly. The leaves wilt and the plant turns dark brownish 
green in color. 
C. —Iron nitrate and (D) iron chlorid in 1 per cent solutions do not affect the tissues 
so severely as the other iron salts. The tissues were not blackened and the accumula¬ 
tions became apparent only upon testing the tissues with a solution of acid thiocyanate 
of potash. 
27135—23-6 
